Products such as insulin are very valuable to those who depend on them. It is therefore possible to recoup the high cost of research and development involved in establishing a genetically engineered process. Nevertheless, there have been some attempts to introduce biotechnological processes for lower-value products. These generally need to be produced on a larger scale.
Protein is an important dietary ingredient. Processes are now available making it possible to produce large quantities of protein-rich microbial cells as feedstuffs for farm animals. The amount of space such processes require is many times less than that needed to produce the same amount of protein from green plants. For example, about 80,000 tons (70,000 metric tons) per year of bacterial protein can be produced in a factory covering only a few acres (hectares). Methanol (made from natural gas) and ammonia are used as the raw materials.
Over the next few years, it is likely that an increasing number of high-value products will be produced biotechnologically. These will come not only from microorganisms but also from large-scale fermentation of both animal and plant cells. Until recently, it has been difficult to maintain cultures of cells from multicellular organisms in a healthy state for long periods. Modern developments in biochemical techniques have now made this possible. New vaccines and important, complex organic molecules could be produced in these ways. In
Strandsof DNAemerge from the bacterium Escherichia coli [above, magnified about 40,000 times). This bacterium is the most frequently used organism for genetic manipulation.
the longer term, biotechnology holds out the hope of producing commodity materials, such as plastics, by fermentation directly from living organisms. This would free us from dependence on diminishing supplies of oil.
Single-cell proteinas food for humans or animals can be made by growing bacteria or yeast. These are grown on various organic materials such as oil, natural gas (methane), and even wood pulp. The process described (below, left) uses bagasse—the waste cellulose from sugar cane—and a bacterium called Cel/ulo-monas in the fermenter. The simple process (belowl employs the yeast Candida sp. in the fermenter and hydrocarbons from an oil refinery to make protein animal feed.
Date: 2015-12-11; view: 1364